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 3. RECOMMENDED APPLICATIONS. A partial listing of recommended applications
for ultrasonic flowmeters is as follows:
Pipe sizes of l/2-inch and larger.
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Raw water, including wells, lakes, rivers, ponds, and springs.
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q Water
treatment plants including influent and effluent.
Wastewater treatment plants including raw sewage, return and
waste-activated sludge, secondary settling tank supernatant, treated
effluent, plant water, tertiary treatment flows, and supernatant
flows, except mixed liquor.
q Industrial
flows including brine, plant effluent, and cooling water.
4. LIMITATIONS. Limitations of ultrasonic flowmeters are dictated by the
degree of entrained solids and gases. One must know if the fluid contains
solids or gases and at what concentration. Other limitations are as follows:
Time-of-travel type requires clean liquids.
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Doppler type is best suited to unclean liquids.
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Excess solids in slurries may block ultrasonic signals.
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Cannot be used on asbestos or cement pipes.
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Pressure rating generally equal to piping system.
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Temperature range for time-of-travel type is -450F to +500F.
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Temperature range for the doppler type is -450F to +250F.
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Outside of pipe must be clean where meter is attached.
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Inside of pipe must be free of scale, rust, and corrosion.
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5. INSTALLATION. A necessary requirement of installing electromagnetic
flowmeters is that the pipe must be clean and free from rust on the outside
end without scale or corrosion on the inside. In the preliminary evaluation
of matching a meter to a system, the following considerations should be
included.
5.1 Meter Choice. The major difference between the two types of ultrasonic
flowmeters is their ability to measure liquids containing different levels of
entrained impurities. The time-of-travel type is designed for clean liquids
while the doppler type will measure dirty, corrosive, and slurried liquids.
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